'  f 


\S 


Circular  No.  81  "" — ^_^' 

United  States  Department  of  Agriculture, 

BUREAU   OK   ENTOMOLOGY. 
L.  O.  HOWARD.   Entomoiogiit  »nd  Chief  of  BuTcmu/t,//""l0>*- 

THE    kPHIDEH    IFFECTING    NIF^^Kt/ 

INTRODUCTION.  V    *■  "  ,•  tf*'  V 

\?fa'' 'eVi'1 

Four  species  of  aphides,  or  "plant-lice,"  coininoin£^fnz0MR!|t$  an^h 

in  the  United  States,  namely,  the  woolly  apple  aphis  (Scfitsenmtftfiani- 
I  [ausm.  .  the  European  grain  aphis  (Siphoeoryru  •<>•■  na  Fab. ).  the 
apple  : ij >  1 1 i -  (Aphis  mali  Fab.),  and  the  rosy  apple  aphis  (Aphis  mali- 
•  Fitch).  The  first  mentioned  the  woolly  apple  aphis-  infests 
the  roots  of  the  apple,  producing  a  knotted,  distorted  growth,  and 
also  the  limbs  and  branches,  where  the  colonies  are  quite  conspicuous 
from  the  white,  flocculent  material  which  the  insects  Becrete.  This 
species  ha-  been  treated  in  Circular  No.  20,  second  series,  of  tin- 
office,  to  which  the  reader  i-  referred.  The  other  specie-  above  men- 
tioned infest  the  more  tender  growing  shoots  and  leave-  of  the  apple, 
and  are  especially  injurious  when  occurring  on  young  orchard  or  nur- 
sery tree-,  which  are  more  commonly  infested  than  older  trees,  making 
comparatively  little  annual  growth.  Water  -proiit-  also  are  frequently 
infested,  and  the  -hoot-  of  top-worked  trees  are  especially  subject  to 
attack. 

The  presence  of  these  insects  i-  indicated  by  the  curled  and  distorted 
condition  of  the  more  terminal  leave-,  and  if  a  plant  showing  these 
symptoms  be  closely  examined,  -mall  oval  or  pear-shaped  soft-bodied 
aphides,  greenish  or  pink  in  color  according  to  species,  will  be  found 
on  the  under  surface  of  the  leave-,  along  the  tender-  stem  or  elsewhere, 
often  practically  covering  these  part-  (see  figure  1). 

Each  aphis  is  provided  with  a  -mall  beak,  which  is  pushed  down 
into  the  tissues  of  the  leaf  or  stem  and  by  means  of  which  the  sap 
i-  sacked  Up  for  food.  When  the  in-ects  are  abundant,  the  drain 
upon  the  plant  i-  very  great,  interfering  with   it-   proper  growth  and 

development,  ami  in  extreme  cases  causing  the  death  of  the  infested 

part-. 

The  leaves  and  -hoot-  of  plants  infested  by  these  in-ects  are  fre- 
quently seen  to  be  covered  with  a  black  substance,  i-  if  dusted  with 

N      - 1  —07 


soot.  This  is  due  to  a  black  fungus  which  grows  on  the  "honey 
dew"  excreted  b}'  the  aphides.  This  may  be  produced  in  such  quan- 
tities as  to  coat  the  leaves,  and  is  attractive  to  various  species  of  ants 
and  wasps  frequently  to  be  seen  attending  the  aphides  or  frequenting 
plants  infested  by  them.  The  black  fungus  noted  is  not  in  itself 
especially  injurious,  bat  it  usually  indicates  the  presence  of  aphides, 

which     mav     be 
v^e>~>-  the  cause  of  ma- 

^%^  terial  injury. 


APHIDES   IN 
GENERAL. 


The  insects  of 
the  family  Aphi- 
didse,  or  "  plant- 
lice,"  are  espe- 
cially remarkable 
on  account  of 
their  mode  of  de- 
velopment. This 
will  vary  con- 
siderably accord- 
ing to  the  species, 
but  at  some  time 
in  the  life  of  a 
species  true  sexes 
are  produced, 
usually  in  the 
fall,  the  sexual 
female  depositing 
eggs  after  the 
usual  manner  of 
insects.  Eggs 
deposited  in  the 
autumn  pass  the 
winter  in  this 
condition,  and 

Fig.  1. — Terminal  shoot  of  apple  infested  with  the  apple'  aphis  [Aphis  mali),  f  Lpj  r  hatch  ill"'    ill 
showing  condition  of  leaves.     (Original.)  _         _      *» 

the  spring  is  more 

or  less  coincident  with  the  revival  of  growth  of  vegetation.  From 
the  winter  eggs  is  produced  a  generation  of  females,  usually  wingless, 
which  reproduce  agamic-ally— that  is.  without  the  intervention  of 
males,  many  species,  as  those  under  consideration,  giving  birth  to 
living  young.  The  adult  aphides  of  this  first  generation  are  termed 
"stem-mothers."  The  offspring  of  the  stem-mothers  (second  gener- 
ics, si] 


ation)  may  be  winged  or  wingless,  or  both  forma  may  occur;  they 
reproduce  agamically,  some  species  being  oviparous  and  depositing 
peeudoova,  or  eggs  which  do  not  require  fertilization  for  develop- 
ment; while  others  are  viviparous  and  bring  forth  young  alive,  the 
peeudoova  developing  within  the  body  of  the  parent.  There  may  be 
u  succession  of  generations  produced  agamically,  with  most  species 
this  mode  of  reproduction  continuing  until  the  approach  of  autumn, 
when  the  true  sexes  appear  and  deposit  eggs;  <>i-  a  species  ma\  be 
more  or  less  biennial,  some  indh  iduals  producing  true  sexes  only  every 
second  year.  With  -till  other  species,  the  true  sexes  of  which  are  at 
present  unknown,  agamic  reproduction  possibly  continues  for  a  series 
of  year*  The  same  species  of  aphide  may  present  several  forms,  as 
wingless  agamic  females,  winged  agamic  females,  and  the  true  sexual 
forms;  in  the  last  the  male  may  be  winged  and  the  female  wing- 
less, or  both  sexes  may  he  wingless.  The  different  generations  of  a 
given  Bpecies  may  vary  more  or  less,  and  in  Borne  instances  this  is  the 
cas  to  such  an  extent  that  they  appeal-  to  belong  to  distinct  Bpecies. 
Aphides  are  enabled  to  increase  with  great  rapidity  by  reason  of  the 
short  time  required  by  their  young  to  reach  maturity.  Their  powers 
of  multiplication  are  so  great  that  if  unchecked  the  product  of  a 
single  insect  during  one  season  would  run  up  into  the  billions.  Very 
fortunately,  however,  there  arc  many  drawbacks  to  their  increase, 
among  which  are  certain  weather  condition-,  parasitic  and  predaceous 
ts,  and  fungous  diseases.  When  one  or  more  of  these  agencies 
are  in  abeyance,  aphide-  may  become  very  numerous  and  destructive 
locally  or  over  a  considerable  ranee  of  territory. 

THE    EUHOPEAH    DRAIN    \rill-. 

I  ih.) 

The  European  grain  aphis  ( fig.  2)  i-  the  common  greenish  apple  aphis 

of  the  United  State-,  and  i-  the  species  erroneously  considered  by  Fitch 
a-  identical  with  the  European  Aphis  iinili  Fab.,  by  which  name  until 
recently    it   ha-   been    very  generally   known   in   our   literature.      Two 

species,  however,  have  been  confused  under  thi-  name,  the  present 
and  the  following1,  which  fact  was  recognized  by  Mr.  Th.  lViLrande-, 
and  also  by  Or.  .1.  B.  Smith.  Prof.  E.  IV  Sanderson  in  \'.{^i  described 
this  inflect  a-  new  under  the  name  of  Aphis  v'--  ',:.  I >ut  Pergande  ha-  sub- 
sequently shown  that  the  insect  i-  identical  with  the  European  grain 
aphisi  Aj'/n's.-  Fab.),  and  consider-  that  the  species  really  belong- 

to  the  genus  Siphocoryru  of  Passerini.  Thi-  species  i-  recorded  from 
various  widely  separated  localities,  and  i-  probably  very  generally 
distributed  throughout  the  United  State-.  Twenty-two  plant-  upon 
which  it  has  been  observed  are  recorded,  comprising  eight  trees,  four 

Is  or  herb-,  and  ten  grains  and  grasses.  <  H  orchard  fruit-,  apple, 
quince,  and  plum  are  food-plant-:  and  of  grains,  rye.  oat-,  and 

ten 


wheat  are  infested,  the  last,  according  to  Prof.  F.  M.  Webster,  often 
being  quite  seriously  injured  by  the  aphides  in  the  fall,  the  yourg 
plants  being  attacked  at  or  just  below  the  ground. 


Fig.  2.— The  European  grain  aphis  (Siphocorynt   aveme),  a  common  aphis  on  apple:  a,  migratory 
,  sexual  female;  c,  antenna  of  migratory  female;  (/,  side  view  of  end  of  body  of  winged 
male;  < .  under  side  of  end  of  body  of  male:  /,  under  side  of  end  of  body  of  sexual  female.     All 
greatly  enlarged  (from  Pergand- 


NATURAL    HISTORY    AND    HAHITS. 


This  species  has  been  well  treated  by  Sanderson  and  Pergande.  and 
has  been  found  to  present  a  very  interesting  life  history.  The  shiny, 
jet-black  winter  eggs  are  deposited  by  the  females  in  the  fall  around  the 
buds  of  the  more  terminal  shoots,  at  crotches  of  limbs,  and  in  cracks 

[Cir.  81] 


and  under  scales  of  the  bark.  The  eggs,  are  quite  -mall.  l>nt  may  be 
readilj  detected  with  the  unaided  eye.  These  batch  in  spring,  about 
the  time  the  young  leaves  of  the  apple  are  pushing  out,  and  the  small, 
enish  '■lire.'*  often  occurring  in  large  numbers,  at  once  attack 
these  parts.  These  insects,  when  fully  grown,  are  the  Btem-mothers, 
and  soon  begin  the  production  of  living  young,  most oi  which  develop 
into  the  winged  agamic  form  which  migrates  to  other  trees  and  toother 
localities,  where  new  colonies  are  Btarted,  the  progeny  of  the  third 
generation  also  being  winged  and  wingless.  In  all,  Borne  five  genera- 
tions of  aphides  develop  on  the  apple,  but  by  early  July  in  the  lati- 
tude of  Washington  the  tree-  are  free  from  them,  and 
the  aphides  have  become  established  on  grains  and 
grasses  <>r  other  host  plants.  Upon  the  approach  of 
fall,  apple  trees  are  again  infested  by  the  return  mi 
grants  from  the  grasses  and  grains,  the  true  females 
are  soon  produced,  and  the  winged  male-  come  from  the 
grasses  upon  which  they  have  developed.  Winter  e 
are  deposited  during  September,  October,  and  early 
v\      ember  in  the  manner  indicated. 

THE    APPLE    APHIS. 

In  general  appearance  the  apple  aphis  (fig.  1 1,  or  apple 
leaf-aphis,  is  much  like  the  preceding,  with  which  it  has 
been  confused.  The  body  is  pear-shaped,  instead  of  oval 
as  in  S.  aven  '.  the  colors  of  both  being  yellowish  green, 
greenish,  or  darker,  varying  considerably  in  detailed 
markings  and  in  the  several  generations. 

■ 

Aphis  malt  Fab.  {pomi  De  Geer)  is  of  European 
origin,  and  has  only  recently  made  it-  appearance  in 
this  country,  Mr.  Pergande  having  first  -ecu  specimens 
collected  in  the  United  State-  in    L897.     However,  at 

I  the 

the  present  time  it  is  widely  distributed,  having  been  ipMi 

recorded  from  New  Jersey,  Delaware.  New  York.  Con-  tw* 

necticut,  Colorado.   Michigan,  Alabama,  and  Georgia. 
The  records  of  thi-  Bureau  -how  it  to  occur  in  Kentucky.  Louisiana, 
Oregon,  Pennsylvania,  Nebraska,  and  Arkansas.     In  this  country  the 
in-ect  appear-  to  infest  apple  (fig.    l)  principally,   if  not   entirely. 
though  in  Europe  it  infests  in  addition  the  wild  crab(Jf^n« 
pear,  and  white  thorn  {CratsegxiA  oxyacanth*  >. 


NATl'KW.     HISTOKY     AM'     li 


The  apple  aphis  has  been  studied  by  Dr.  J.  B.  Smith  and  Trot    E.  Di 
Sanderson.     Winter  eggs  (fig.  3)  are  deposited  by  the  sexual  females 

[Ox  - 


in  the  fall,  oviposition  beginning  somewhat  earlier  than  but  overlap- 
ping with  that  of  the  preceding  species;  they  are  placed  in  similar 
situations,  and   are   not   distinguishable   from  tho.-e  of  Siphocoryne 


Fig.  i — Apple  aphis  (Aphis  mali);.  a,   winged  agamic  form;  6,  pupa;  e,  wingless  agamic  form;  d, 
recently  born  aphis.    All  greatly  enlarged  (original). 

avenx.  The}'  hatch  perhaps  somewhat  later  in  the  spring,  and  after 
the  foliage  is  further  advanced  and,  like  the  species  next  considered, 
the  aphides  developing   from   them  cause    a  greater  curling  of  the 

leaves.      The    apple    leaf 


TnamTTTr^cs^gfea 


aphis  infests  the  apple 
throughout  the  year  and 
for  this  reason  is  capable  of 
more  injury  than  the  other 
species  herein  treated. 
Upon  the  hatching  of  the 
winter  eggs  in  spring  a 
succession  of  agamic  gen- 
erations is  produced,  the 
earlier  ones,  except  the 
first,  with  numerous  winged 

Fig.  5.— Apple  aphis  [Apkis  mali):  The  true  sexual  forms:    individuals    which    migrate 
a.  male;  b,  female.    Greatly  enlarged  (original).  .  ,         .    , 

to  other  trees  and  estab- 
lish new  colonies.  In  New  Jersey,  as  found  by  Doctor  Smith,  there 
may  be  during  the  season  seven  agamic  generations  followed  by  the 
development  of  the  sexual  wingless  male-  and  females  (fig.  5)  in  the 
fall. 

[Cir.  SI] 


Till     ROM      U'l'l.i:     Mill-. 

Tin'  rosy  apple  aphis  (fig.  ft),  regarded  by  Pergande  aa  Aphis  rnali- 
folia  Fitch,  and  determined  bj  Sanderson  a-  Aphi*norbi  Kaltenbach, 
i-  readily  distinguished  from  the  preceding  by  its  larger  size,  rounder 

body,  and  usual  1)  rosj  color,  which, however,  may  \ar\  from  sal n 

to  tan  or  even  to  slat)  gray  or  black,  the  bod)  I  ><  ■  i  i  >  -_r  covered  with  a 
whitish  pulverulence.  This  species  is  verj  general!)  distributed  in 
the  United  States,  occurring  in  Buch  widely  separated  States  ;i-  Illi- 
nois, Connecticut,  New  Jersey,  Virginia,  Washington,  California, 
Sotiih  Carolina,  and  West  Virginia;  it  occurs  also  in  Canada,  rhe 
species  is  common  on  apple,  hut  has  been  taken  by  Sanderson  on  pear. 


born  aphis.    All  L-rently  enlarge  I 

In  Europe  tin'  food  plant-  <>f  Aphis  eorbi,  in  addition  t.»  apple,  are 
yaccintha,  S>>r!>"s,/,i<'i/j>,i/->'i,  S.  domestica,  ami  S.  /"/•/>"/" 

in  e  Hiarrom . 

The  life  history  of  this  species  i-  but  imperfectly  known.  Winter 
eggs  an>  deposited  in  tin-  autumn  by  sexual  females,  and  more  often 
on  tlio  trunk  and  larger  limbs  than  with  the  other  spe<  ies  mentioned. 
They  hatch  in  spring  as  the  apple  leave-  are  pushing  out,  and  theyoung 
aphides  infest  the  young  leave*  and  later  the  tender  -hoot-  ami  foliag 
the  latter  thus  becoming  usually  badly  curled.  Three  generations  from 
the  egg  are  said  to  occur  on  the  apple  in  the  spring,  many  individuals 
of  the  second  and  third  generations  developing  wings  ami  migrating 
toother  trees  and  toother  host  plant-.  After  the  third  generation 
the  apple  i-  deserted  by  the  insects  until  fall,  when  the  return  migrants 
appear  ami  give  rise  to  the  true  sexual  form-,  the  females  deposil 
eggs  a-  described. 

•   Ml 


NATURAL  ENEMIES  OF  APHIDES. 


Aphides  are  attacked  by  various  species  of  predaceous  and  parasitic 
enemies,  and  by  fungous  diseases,  and  under  certain  climatic  conditions 


Fig.  7.-Two-spotted  ladybird  {Adalia  bipunctala):  a,  larva,  b,  mouth  parts  of  same;  c  claw  of  vftme- 
rf.  pupa;  - .  adult  or  beetle;  /.  antenna  ol  same,  a  common  arboreal  ladybird.  All  enlarged  'from 
Marlatt). 

these  agencies  exert  a  very  important  influence  in  their  control.     Species 
of  ladybirds  or  Coccinellidaa  (fig.  7).  aphis  lions— the  larvse  of  Chryso- 


Pig.  8.— The  golden-eyed  lace-wing  lly  (Cftrysoj :utata):  a,  eggs;  b,  full-grown  larva;  e,  foot  of 

same;  </.  larva  devouring  an  insect;  e,  COCOOD; /,  adult  insect:  g,  head  of  same:  ft,  adult    natural 
size.    All  enlarged  except  ft  (from  Marlatt). 

pida«  (tig-.  8)  and  Hemerobiida — and  the  larv;e  of  syrphus  flies  prey 
upon  the  apple  aphides,  which  are  destroyed  also  by  small   hymenop- 

[Cir.ei] 


9 

teroua  parasites.  Under  certain  weather  conditions  entire  colonies 
1 1 1 : i  \  be  destroyed  by  fungous  diseases.  During  periods  of  rainy 
weather  the  insect  enemies  of  aphides  are  much  less  active  than  when 
the  weather  is  fair.  This  is  particularly  true  of  the  minute  delicate 
winged  bymenopterous  parasites,  to  which  Buoh  weather  conditions 
are  largely  fatal.  With  the  coming  of  fair  weather,  however,  these 
foes  of  aphides  soon  multiply,  quickly  reducing  their  boats  to  much 
less  injurious  numbers. 

Mi  I  n<  >l>-   OF   O  IMTROL. 

/'  \ming.  As  l»:i~-  been  stated,  the  aphides  under  consideration  pass 
the  winter  in  the  egg  stage  od  the  apple,  the  eggs  being  deposited 
more  <>r  less  promiscuously  over  the  more  nearly  terminal  twi 
With  young  trees  especially,  which  are  seen  to  be  heavily  stocked 
with  tin'  eggs,  the  latter  may  be  largely  removed  during  the  work  of 
pruning,  and  the  pruninga  should  be  collected  and  burned. 

The  insects  in  the  egg  condition  are  frequently  distributed  on  nursery 
stock;  therefore,  it'  in  planting  trees  this  stock  be  well  pruned  and  the 
pruninga  destroyed,  the  establishment  of  the  aphides  in  young  orchards 
may  be  often  prevented  or  delayed. 

Winter  spraying  for  destruction  of  eggs. — Several  -pray-;  have  been 
at  various  times  more  or  less  used  for  the  destruction  of  the  e<_r!_r-  on 
the  trees;  among  these  are  strong  lye  water,  whale-oil  soap,  and  kero- 
-ene  and  crude  petroleum  in  soap  or  mechanical  emulsions  with  water 
or  evt  11  undiluted.      On  the  whole,  very  little  of  practical  good  seems 

to  have  followed  these  treatments,  the  eggs  being  largely  resistant  to 
Buch  insecticides  as  are  not  bo  strong  as  to  injure  the  trees.  In  the 
experience  of   Prof.  .1.  M.  Aidrich,  however,  excellent  results  have 

followed  the  086  of  lime-sulphur  wash,  most  allot'  theeggsof  the  apple 
aphis  having  been  destroyed  by  one  thorough  application  in  spring 
shortly  before  the  buds  opened.     The  use  of  this  wash  for  the  eggs  of 

aphides  would  also  control  the  San  Jose  scale  when  present. 

Spring  and  summer  truitmriit*.     Ktl'ective  work  in  controlling  these 

insects  may  be  done  in  the  spring  just  after   they  have    hatched   from 

eggs  and  have  collected  on  the  expanding  foliage.  Tree-  Been  to  tie 
badly  infested  at  this  time  should  be  thoroughly  -prayed,  taking  pain- 
to  wet  as  completely  a-  possible  all  part-  of  the  leaves,  twigs,  and 

branches.  However  thoroughly  the  work  may  be  done,  some  of  the 
"'lice  "  are  almost  sure  to  escape  destruction,  owing  to  the  difficulty  of 
forcing  the  spray  between  the  unfolding  leaves,  more  or  less  covered 

with  hair-,  where  some  of  the  in-ect-  will    have  penetrated.      A  -u 
quent  treatment  in  the  cour-e  of  a  week  should  usually  lie  made,  espe- 
cially if  the  first  application  i-  -.en  to  have  been  unsatisfactory. 

After  the  foliage  is  well  out  and  more  or  less  distorted  from  the 
presence  of  the  aphide-.  effective  Bpraying  is  quite  difficult,  - 

[Cir.Mj 


10 

many  of  the  insects  on  the  lower  surface  of  the  curled  leaves  will  not 
be  hit  by  the  spray.  Repeated  applications  must  be  made,  therefore, 
as  necessary  to  keep  the  insects  under  control.  It  will  often  be 
found  practicable  to  bend  over  and  immerse  the  terminal  shoots  of 
badly  Infested  young-  trees  in  a  bucket  of  the  spray  solution,  and  *'us 
treatment  will  be  very  effective. 

Spray  misatures. — The  lime-sulphur  wash  for  the  destruction  of  win- 
ter eggs  is  made  according  to  the  usual  formula  for  the  wash,  namely, 
lime  20  pounds,  sulphur  15  pounds,  water  to  make  50  gallons,  and 
boiled  for  one  hour. 

After  the  trees  are  in  foliage,  a  more  dilute  contact  insecticide  must 
be  employed,  as  strong  tobacco  decoction,  15  or  20  per  cent  kerosene 
emulsion,  15  per  cent  crude  petroleum  emulsion,  or  whale-oil  soap  at 
the  rate  of  1  pound  for  each  -1  gallons  of  water.  Since  aphides  secure 
their  food  b}r  sucking  up  sap  from  within  the  plant,  none  of  the 
arsenical  poisons  would  be  effective. 

Tobacco  decoction  may  be  made  from  tobacco  stems  and  other 
refuse  tobacco  by  boiling  at  the  rate  of  1  pound  for  each  1  or  2  gal- 
lons of  water,  sufficient  water  being  added  to  make  up  for  that  lost  in 
boiling. 

A  20  per  cent  kerosene  or  crude  petroleum  emulsion  is  made  as 
follows: 

Whale-oil  or  other  soap pounds..     2 A 

Kerosene  or  crude  petroleum gallons. .     10 

Water  to  make gallons. .     50 

The  soap  is  dissolved  in  5  gallons  of  hot  water,  which  is  at  once 
poured  into  the  spray-pump  barrel.  The  10  gallons  of  kerosene  or 
crude  petroleum  is  next  added  and  the  whole  thoroughly  emulsified 
by  pumping  it  back  through  the  hose  into  the  barrel  for  6  or  8  min- 
utes. After  the  oil  has  become  thoroughly  emulsified,  the  barrel  ifi 
filled  with  water,  and  the  preparation  is  ready  for  use.  When  a  less 
amount  of  emulsion  is  desired  than  the  quantity  above  indicated,  it 
may  be  reduced  as  desired  by  observing  the  proportions  given. 

Approved : 

James  "Wilson, 

Secretary  of  Agriculture. 

Washington,  D.  C,  December  18,  1906. 

[Cir.81] 


o 


WASHINGTON      „  )VC     svts 


UNIVERSITY  OF  FLORIDA 


3  1262  09216  4499 


